Carbon-holder for electric furnaces.



P: L. T. HERGULT,

CARBON HOLDER FOB. ELECTRIC FURNACES.

APPLIOATIOE FILED EEPT 7, 1910. l fi Patented. Apr. 11, 19M.

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INVENTOR 4 P, L. T. HEROULT.

GARBON HOLDER FOR ELEOTEIG FURNACES.

APPLICATION FILED SEPT. 7, 1910.

@QQJQS Patented 11, 1911.

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6mm QM *w UNITED STATES PATENT OFFICE.

PAUL If. T. HEROULT, OF LA PRAZ, FRANCE, ASSIGrNOIt TO SOCIETE ELECTRO-METALLURGIQUE FRAINGAISE, OF FROGES, FRANCE.

Specification of Letters Patent.

Patented Apr. 11, 1911.

Application filed September 7, 1910. Serial No. 580,806.

To all whom it may concern:

Be it known that 1, PAUL Louis Tous- SAINT HimoULT, a citizen of theRepublic of France, residing at La Praz, Savoie, France, have inventedcertain new and useful Improvements in Carbon-Holders for ElectricFurnaces, of which the following is a specification.

In the operation of electric furnaces, diffiwhy has been experienced byreason of the heating of the metal carbon holders or clamps throughwhich the current is transmitted to or from the carbon pencil orelectrode. Such heating is due to imperfect contact between the metalsurfaces and the carbon. It has been common to circulate water or othercooling fluid through a ductor passage in or adjacent to the carbonholder in order to keep it cool. This has not however sufliced toprevent destructive arcing and consequent disintegration of the carbonat the surfaces where the imperfect contact exists. Y

The present invention aims to provide means for keeping the carbonholder suitably cooled, and for diminishing the genera-- tion of heatthrough imperfect contact at the contacting surfaces.

The present invention is shown in the accompanying drawings as embodiedin a suitable construction of carbon holder, this being deemed thepreferable embodiment of the invention.' i Figure 1 is' an elevation ofthe carbon showing the holderapplied to it; Fig. 2 is an'end view orelevation of the holder on a larger scale; Figs. 3 and 4 are radialtransverse sections of the holder upon a still larger scale, on thelines 3-3 and 44; Fig. 5 is an oblique elevation of the Water coolingcore or duct; Fig. 6 is a cross-section on the line 6-6 in Fig.2 on thesame scale as Figs. 3 and 4:; Fig. 7 is a view corresponding to Fig. 2but showing a somewhat modified construction; Fig. 8 is a radialtransverse section of part of Fig. 7 on the line 8'8; Fig. 9 is a viewof a further modification.

In 1, A is the carbon pencil or electrode, which may be cylindrlcal or,of any other suitable shape, and B is as a whole the carbon holder. Thelatter is constructed as a clamp completely or partially encircling orinclosing the carbon. If the carbon is cylindrical, the holder will beshaped. as an approximately circular ring as shown in Fig. 2. This ringmay be divided on one side a as in Fig. 2, or at opposite sides a b asin Fig. 7. At the divlsion a (or each division a b) the clamp is formedwith flanges c 0 through which pass a tightening screw or bolt at havingone or more nuts 6. To render the holder sufficiently flexible toreadily adapt itself to slight irregularities in the surface of thecarbon, it is slitted radially on its inner side at f f, and on itsouter side at g g at suitable intervals, the inner and outer slitsbeing. staggered or alternated as best shown in Fig. 2.

The carbon holder may be supported and connected in any suitable waywith the source of current} a common construction being to form thecarbon holder with a projection or arm B which is bolted or clampedtightly to a supporting and conducting bar '6, which connects in anysuitable way with the current generator. The arm B" is shown as clampedto the bar C by bolts D. For cooling the carbon holder, a duct orpassage E is provided which is best con structed as a tube of iron orother metal of suitably high-melting point, and which fortheconstruction of holder shown in Fig. 2 is best bent to approximatelythe shape shown in Fig. 5. That is to say the Water or other coolingfluid entering at it passes in straight direction through the arm B andthen traverses in the bent portion z' of the tube the curved portion ofthe holder, is then" bent into the lug 0 where it forms an eye or loopj, returning thence at z" parallel to the portion 2' and traversingsubstantially the entire circumference of the clamp, again bent into aneye 3" within the opposite lug c, and returning in a curve 71" to thearm B, which it traverses as an outlet ortion is of the tube from whichthe uid emerges.

Preferably the main portion of the holder B is in ade of copper, brass,or other suitable metal more fusible than the tube E, and is castuponand around this tube so that the tube is embedded in it in a mannerclearly of these loops is to cool the metal around the being clampingscrew, and thus to cool the screw and its nuts. The depth and spacingofthe slits f and g are such with relation to the mass and conductivityof the carbon holder, that a suiiicient cross section of the latter isretained between the nearest approaching portions of the respectiveslits to afford ample conductivity to carry the required current.

In tightening the carbon holder upon the carbon, either the screw d orthe nuts 6 are turned so as to draw togetherthe lugs 0 c and therebycontract the holder upon the carbon. In so doing the lugs 0 0 changetheir relative planes so that if originally parallel they becomeinclined the one relatively to the other. This would tend to bend ordistort the tightening screw d if the parts were inflexibly united. Itis preferable therefore to provide a compensating or self-adjusting orrocking bearing between the nuts 6 e and the lugs c 0. This is best doneby forming the nuts with their surfaces which bear against the lugs, assegments of spheres (or it may be as segments of cylinders), thesebearing against surfaces on the lugs which conform to them. It ispreferable to make the nuts non-rotative, and to make the screw d aright-and-left thread screw with squared ends to be engaged by a key forturning it. To make the nuts nonrotative it is desirable to form themwith ears having holes which are loosely engaged by screws m m (Fig. 6)which fasten them to the lugs 0, but in so loose a manner that the nutis free to rock upon the screws m to adapt itself to the varyinginclination of the lugs relatively to one another.

'When the carbon holder has been clamped tightly upon the carbon, wateror other cooling fluid is circulated through the pipe or duct E, andupon causing the electric current to pass through the holder to thecarbon (or vice versa) the heat generated at their contacting surfacesis largely taken up by the circulating water, which thereby counteractsthe tendency of the holder to expand circumferentially under heat andthereby relax its grip upon the carbon, the effect of which would be' torender the contacting surfaces more imperfect and thereby to generatestill more heat. The holder is thus by reason of the water circulationmaintained of substantially uniform contraction upon the carbon. Myinvention, however, goes beyond this in that it introduces acompensating effect to at least partially offset any slight expansion ofthe carbonholder. This is dueto the inner slits f f which divide themetal of the holder into separate segments f slightly spaced apart fromone another, and which when heated expand mainly or partly toward thecenter, since the cooling effect of the duct E is tomaintain the-portionof the holder adjacent to it so cool that it cannot materially expand,and

hence any expansion due to the heating of these inner portions betweenthe slits necessarily results in their approaching the center, andthereby contracting the holder more firmly upon the carbon as the heatincreases. Thus the effect of the generation of heat through imperfectcontact is to partially or even entirely compensate for any expansionsuch as would make the contacts more imperfect, and may even so contractthe holder upon the carbon as to diminish the imperfection of contactwhich caused the heat and thereby diminish. the generation of heat. Thisefiect can be accentuated by prolonging the slitted internal portion ofthe holder inwardly, as indicated in Fig. 7 where the cooling duct E isshown located closer to the outer than to the inner part of the holder,so that the separate inner segments f between the slits f are givengreater radial length, so that their expansion under heat is moreeffective to contract the holder upon the carbon.

The shape of the holder may be variously modified in accordance with theshape of the carbon to which it is to be applied. For example in Fig. 9is shown a holder adapted for a square carbon, in which case the outerportion of the holder instead of being equally square, is preferablycurved in an approximation'to a. circle, whereby to afford the mosteffective circumferential resistance to the outward thrust of theinterior segments f as they expand under heat.

The invention may be variously modified, as will be apparent to thoseskilled in the art, without departing from its essential features. Inthe broader aspects of my invention I do not regard the looping of thecooling tube at 7' j within the lugs, as indispensable.

What I claim is 1. A carbon holder comprising a metal clamp adapted toembrace the carbon, having means for cooling it, having aportioncircumferentially intact to afford tensile strength and internallyslitted to form segments capable of expansion toward the center underheat.

2. A carbon holder comprising a metallic clamp adapted to embrace thecarbon, having a portion circumferentially intact and having therein aducttraversing it in circumferential direction through which tocirculate a cooling fluid, and internally slitted to form segmentscapable of expansion toward the center under heat.

3. A carbon holder comprising a metal clamp adapted to embrace thecarbon, having means for cooling it, and slitted both internally andexternally.

4. A carbon holder comprising a metallic clamp adapted to embrace thecarbon, having a duct traversing it in circumferential direction throughwhich to circulate a cooling fluid, and slit-ted both internally andexternally.

5. A carbon holdercomprising a metallic clamp adapted to embrace thecarbon, and having ears and a clamping screw for drawing said earstogether to contract the clamp, provided with a duct traversing it incircumferential direction looped in said ears to encircle said screw.

6. A carbon holder comprising a metal clamp adapted ,to embrace thecarbon, ha-ving a portion circumferentially intact, and radially slittedto increase its flexibility, and a cooling duct'consisting of a tube ofmetal of higher melting pointthan said clamp, traversing it incircumferential direction,

and embedded in the clamp by the casting of the latter around said tube.

7. A carbon holder comprising a metal clamp having ears and a clampingscrew for drawing said ears together, a nut engagingsaid screw having arocking engagement with one of said ears, and fastening means forholding said nut against said car while i leaving it free to rockthereon.

In witness whereof, I have hereunto signed my name in the presence oftwo subscribing witnesses.

PAUL L. T. HEROULT.

